Police in New Haven have charged the laboratory technician Raymond Clark with murdering Annie Le, the Yale University student found dead this week.

The warrant charging 24-year-old Clark is sealed and police have declined to discuss the evidence against him. But officials have previously indicated the case turns on DNA and other forensic evidence collected from a utility shaft behind a wall in a research facility where Le was found strangled, four days after her disappearance.

Clark was arrested early today at a budget motel about 25 miles away from the Yale campus. He had been under police surveillance.

Clark kept his head bowed during a brief court appearance today, where he entered no plea on the murder charge. He was then jailed in lieu of $3m (£1.8m) bond.

Annie Le. Photograph: AP

The New Haven police chief, James Lewis, told reporters: "This is not about urban crime, it's not about university crime, it's not about domestic crime, but about workplace violence, which is becoming a growing concern around the country."

The FBI said lie detector specialists and its "behavioural analysis" teams played a key part in the investigation. Nearly 300 items were seized in the case and investigators viewed hundreds of hours of video surveillance.

Clark was arrested on Tuesday night while investigators searched his home and took a DNA sample and then released. He was arrested again without incident on the warrant early this morning. Police have described him as generally co-operative.

In a case that has horrified the university community and gripped the US, the body of Le, 24, was found in a utility shaft in a heavily secured research building on the campus on the day she was to be married.

Clark worked as a custodian at the laboratory where Le conducted research. One of his duties was cleaning the cages where the experimental rodents lived, an occupation that is likely to have brought him into contact with Le. Police have declined to discuss the relationship between the two.

Yale's president, Richard Levin, said Clark had worked at the university since December 2004, and that nothing in his employment record foreshadowed violence.

"It is very disturbing to think that a university employee might have committed this crime," he said, stressing that the campus and the city are safe.

"What happened here could have happened anywhere," he said. "It says more about the dark side of the human soul than it does about anything else."

"This incident could have happened in any city, in any university, or in any workplace. It says more about the dark side of the human soul than it does about the extent of security measures," Levin said in a message sent to the Yale community.

Friends and neighbours described Clark as an animal lover who lived with his girlfriend. "He was a nice kid, he was a jokester, everybody knew him," high school friend Lisa Heselin told CNN.

Le went missing on Tuesday morning of last week, having left her wallet, keys and purse in her office in a medical school building about a mile from Yale's main campus. She was filmed by surveillance cameras during her final walk to the facility where her body was found on Sunday.

Access to the basement laboratory where Le's body was found is tightly controlled and workers can only enter by ID swipe cards, limiting the pool of potential suspects. The pavement outside the building is closely monitored by surveillance cameras.

By early this week police had narrowed their focused to Clark and ultimately searched his vehicle and his apartment. Investigators tested DNA taken from Clark against evidence collected from the scene.

On the day Le's body was found she had been due to marry Jonathan Widawsky, a 24-year-old physics student at Columbia University in New York. The couple met as undergraduates at the University of Rochester in western New York state. Le was from California.